Despite a full-scale multinational search-and-rescue operation, Malaysia Airlines flight MH370, carrying 239 passengers and crew from Kuala Lumpur to Beijing, remains missing. The Chinese government and its people are particularly frustrated with the slow progress of the investigation, because almost two-thirds of the passengers came from China.

After the mysterious disappearance, reports emerged that two Europeans listed on the passenger manifest were not aboard. The exposure immediately raised a fear that the users of two stolen passports could have boarded the craft to launch a terrorist attack.

The fear was compounded by the fact that, one week before, terrorists launched a heinous attack in the southwest Chinese city of Kunming that left 29 people dead and 143 others injured.

Even worse, the disappearance coincided with the attention-grabbing annual sessions of the National People's Congress and the Chinese People's Political Consultative Conference in Beijing, the destination of the flight.

Although Interpol tends to believe that the two Iranian passengers travelling on stolen passports were not involved in terrorism, there are many other security analyses pointing to a high probability of terrorism. Investigators from Malaysia, China and other countries have not ruled out terrorism as a cause of the air tragedy.

In particular, China is not unfamiliar with terrorist violence targeted at its civil aviation.

In March 2008, a 19-year-old Uygur woman boarded China Southern Airlines flight CZ6901 with a hidden bottle of flammable liquid. When the aircraft was en route from Urumqi to Beijing, she was found to be trying to set it on fire. The plane had to make an emergency landing in Lanzhou . Two men were also detained for being involved in the foiled attack.

In June 2012, when Tianjin Airlines flight GS7554 was flying from Hotan to Urumqi, six Uygur men aboard dismantled an aluminium crutch and turned it into pipes for use as weapons and attempted to hijack the plane. The attackers stormed the cockpit, but were subdued by passengers and crew. Ten passengers and crew suffered injuries in the clash, and two attackers died later from injuries.

A worrying revelation concerning the missing aircraft is that, prior to its take-off, neither Malaysia nor China checked the validity of the two stolen passports against Interpol's "Stolen and Lost Travel Documents" database, although such information was available.

The database, created following the September 11 attacks, aims to help member states secure their borders and protect their citizens from terrorists and other dangerous criminals using fake travel documents. It contains information on travel documents, such as passports, identity documents and visas, which have been reported stolen or lost. The database is useful for the civil aviation authorities of Interpol's member states, but it cannot include information on all fake travel documents. Certainly, some of those which ended up in the hands of terrorists were not covered by the database.

The media coverage of the two stolen passports highlighted the booming black market in fake travel documents in Thailand. The use of fake identity documents is rampant not only in Thailand or even Southeast Asia. The situation in China is also serious, if not worse.

It was reported this January, for example, that the Chinese police discovered and nullified 790,000 forged identities in a nationwide campaign against identity fraud. The campaign was related to the high-profile case of a wealthy Chinese woman dubbed "Sister House" for buying more than 40 properties in Beijing by using various fake identities in order to circumvent restrictions on property purchases. She was sentenced to three years in prison for forging identity cards and other official documents.

In China, advertisements for fake identity documents are easily found in many public places or on websites. Media reports on incidents of identity forgeries are abundant. There are many such reports, for example, about the east gate of Renmin University in Beijing, a notorious black market for trafficking in fake certificates.

Even if the two Iranians had nothing to do with terrorism, their presence on the plane was enough to reveal an alarming security lapse on the Malaysian side.

The Malaysian airline cannot escape responsibility for what has occurred. Part of the blame may also be pinned on the Chinese side. After all, the tickets of the two Iranians were purchased from China Southern Airlines, which had a code-share agreement for the flight. Moreover, China should have applied stricter security standards by screening the passport data of all incoming international passengers.

The rampant use of fake travel documents presents a terrorist threat to aviation security. Individual countries alone cannot address this problem. In this respect, strong and effective international co-operation is extremely important.

The international hunt for the missing plane is still under way. Before the plane's data recorders are recovered and carefully analysed, nobody can be sure of the reasons behind its disappearance. For the time being, however, hard lessons on aviation security must be drawn from this shocking incident.

Zhou Zunyou is head of the China section at Germany's Max Planck Institute for Foreign and International Criminal Law

This article appeared in the South China Morning Post print edition as: